Coexistent yellow nail syndrome and selective antibody deficiency.

BACKGROUND: Yellow nail syndrome (YNS) is a rare, often underdiagnosed condition of unknown origin. The clinical features of the syndrome include yellow nails, chronic sinusitis, bronchiectasis, pleural effusion, and lymphoedema. Despite the frequent occurrence of upper and lower respiratory tract infections in patients with YNS, comprehensive analysis of their humoral immunity has not been previously reported. OBJECTIVE: To present the case of a patient with YNS whose recurrent upper and lower respiratory tract infections may have been caused by an underlying selective antibody deficiency that manifests as impaired IgG antibody response to polysaccharide antigens. METHODS: The patient underwent cultures of purulent sputum for Streptococcus pneumoniae and Haemophilus influenzae, bronchial washings for H. influenzae, and nail scrapings for fungi. Her serum levels of IgG, IgA, IgM, IgG subclasses, and serum titers of IgG antitetanus toxoid, anti-H. influenzae, and anti-S. pneumoniae antibodies were measured. RESULTS: Cultures of purulent sputum were positive on multiple occasions for S. pneumoniae and H. influenzae and bronchial washings were positive for H. influenzae. Nail scrapings were consistently negative for fungi. She had no reductions in serum levels of IgG, IgA, IgM, or IgG subclasses and had normal serum titers of IgG antitetanus toxoid antibodies. However, she demonstrated impaired IgG antibody responses following immunization with Pneumovax and an H. influenza B vaccine. CONCLUSIONS: This case report describes the first comprehensive analysis of humoral immune function in a patient with YNS. The finding of a selective antibody deficiency in our patient provides a potential explanation for the occurrence of respiratory infections in YNS. Accordingly, we recommend that functional antibody determinations and quantitative serum immunoglobulins be evaluated in patients diagnosed as having this unusual, enigmatic syndrome.